Exemplary embodiments of the present invention relates to a transmitter, a receiver, and a method thereof in a human body communication system, and more particularly, to a transmitter, a receiver, and a method thereof in a human body communication system capable of more efficiently and stably transmitting and receiving data by selecting a combination of optimal receiving electrodes when two transmitting electrodes and a plurality of receiving electrodes are used in the human body communication system used for a capsule type endoscope, or the like.
A background art of the present invention is disclosed in Korean Patent No. 0522132 (Published in Oct. 10, 2005).
Various sensing apparatuses for collecting medical information from an inside of a human body have developed. However, it is very important to develop a technology of transmitting collected information to an outside of a human body in addition to the information collecting technology.
An example of a general data transmission method may include a communication cable scheme used for an endoscope, which has been developed for observing an internal state of a stomach. The communication cable scheme mainly inserts a cable configured of a wire or an optical fiber into a human body through a patient's throat. The communication cable scheme has high reliability and makes quality of data collected from the inside of the human body, but causes a severe pain to patients that will be subjected to an endoscopic operation.
In order to solve the problems, Given Imaging Co. in Israel developed a capsule type endoscope of brand name ‘M2A’. The capsule type endoscope is a tablet form unlike the existing gastroscope or colonoscope. Therefore, when a user eats the capsule type endoscope through a mouth, images of the inside of a gullet, a stomach, a small intestine, and a large intestine are photographed by an image sensor in the capsule type endoscope. Further, the capsule type endoscope may transmit the photographed image data to a receiver at the outside of the human body through wireless communication and may be stored in the receiver.
However, the capsule type endoscope adopts a radio wave scheme as a signal transmission scheme and as a result, may consume a considerable amount of power, shorten operating time, be interfered with various electromagnetic waves from the outside of the human body, and have a degraded receiving sensitivity, Further, the capsule type endoscope includes a modulation circuit converting video signals into high frequency signals, and a wireless transmitter such as an antenna for transmitting signals, or the like, and as a result, may have an increased volume, increase production costs, and damage the human body due to the use of the high frequency. Therefore, a human body communication system capable of transmitting data in the inside of the human body to the outside of the human body by low frequency current using the human body as a wire.
However, in the human body communication system in accordance with the related art, current is generated by a potential difference between the transmitting electrodes formed on a surface of a capsule type endoscope injected into the human body and flows through the human body to induce voltage between two receiving electrodes mounted on the surface of the human body, thereby allowing the receiving apparatus to receive the data in the human body. However, in the case in which only the two receiving electrodes are used as described above, voltage is not induced or becomes small in the receiving electrode when a direction of current is vertical to an arrangement direction of the receiving electrodes, such that a receiving apparatus at the outside of the human body cannot accurately receive the signal transmitted from the capsule type endoscope.
Further, when the current generated by the potential difference between the transmitting electrodes of the capsule type endoscope reaches the receiving electrodes through the human body, the voltage is induced according to a distance between the transmitting electrode and the receiving electrode. In actual, when the signals transmitted from the inside of the human body reach the receiving electrodes through the human body, the voltage value is reduced from several thousand of times to tens of thousands of times and the signal interference occurs due to electromagnetic noises induced from the human body, such that the receiving electrodes cannot accurately receive the transmitting signals.